In recent years, various physical training apparatuses are available in the market as people would like to pay more and more attention on their health. Each physical training apparatus has a particular function; wherein the wrist training apparatus is particularly devised for strengthening the wrist muscle as well as enhance the blood circulation thereof. In addition, to make sure that the users have a sufficient exercise, most of the wrist training apparatuses are equipped with a counter for counting the number of the wrist rotation that users have made.
FIG. 1 is a schematic cross-sectional view of a conventional wrist training apparatus. As shown, the conventional wrist training apparatus 100 includes a housing 110, a rotation component 120, a signal emission assembly 130 and a counter 140. The rotation component 120 is disposed in the housing 110 and includes a shaft 121 and an annular wrapper 122, which is configured to wrap the shaft 121. The annular wrapper 122 has an outer surface 123, an inner surface 124 and a receptacle hole 125 extending from the outer surface 123 to the inner surface 124. The signal emission assembly 130 is disposed in the receptacle hole 125; and the counter 140 is disposed in an opening 111 of the housing 110.
The rotation component 120 is driven to rotate along its rotational axis with the wrist training apparatus 100 in rotating, so that the physical training effect is achieved due to the rotation generating the centrifugal force and the centrifugal force equivalently causing the wrist training apparatus 100 having an increasing weight. In addition, because the signal emission assembly 130 is fixed on the rotation component 120 and is driven to rotate with the rotation component 120 in rotating, the counter 140 can count the number of the rotations that the wrist has made according to the signals provided from the signal emission assembly 130. Because the signal emission assembly 130 rotate with the rotation component 120 in rotating, it is important to develop a mean to dispose the signal emission assembly 130 in the receptacle hole 125 in a stable and easy manner.